The present disclosure relates to a punching device which performs punching processing for forming punch holes in a sheet, an image forming apparatus including the punching device, and a punching method for forming punch holes.
A punching device is known which performs punching processing for forming punch holes in each sheet discharged from a main body of an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunctional peripheral having the functions of those apparatuses. In general, the punching device and other devices performing stapling, center folding, and other processing are unitized as a post-processing apparatus, which is connected to the main body of the image forming apparatus for use.
In this type of punching device, conventionally, the position for performing the punching operation has been fixed. Therefore, if the sheet transported to the punching device is inclined with respect to the sheet transport direction, the punching processing cannot be performed at an appropriate position of the sheet. As a result, the punched position will vary for each sheet, leading to degradation in appearance when the sheets on which the holes were formed are bound. Thus, a punching device has been proposed which is configured to be movable in the direction orthogonal to the sheet transport direction, for making it possible to adjust the position in the orthogonal direction at which the punching device will perform the punching processing.
Further, for punching a plurality of holes along the sheet transport direction, in order to correct the position in the orthogonal direction for the punching device to perform the punching processing in accordance with the inclined state of the sheet, there is a case where the position of an edge of the sheet in the orthogonal direction is detected and the position for the punching device to perform the punching processing is determined on the basis of the detected edge position.